<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>动画</title>
    <style>
        @keyframes myfirst
        {
            from {
                background-color: #21D4FD;
                background-image: linear-gradient(45deg, #21D4FD 0%, #B721FF 100%);
                box-shadow: 5px -5px 10px #b8b7b7;

            }
            to {
                background-color: #FAACA8;
                background-image: linear-gradient(197deg, #FAACA8 0%, #DDD6F3 100%);
                box-shadow: 5px 5px 10px #b8b7b7;

            }
        }
        div{
            border-radius: 300px 300px 300px 300px;
            margin: 30px;
            width: 300px;
            height: 300px;
            background-color: #21D4FD;
            background-image: linear-gradient(45deg, #21D4FD 0%, #B721FF 100%);
            box-shadow: 5px -5px 10px #b8b7b7;

            animation: myfirst 5s;
            -webkit-animation: myfirst 5s;
            /*animation: myfirst 2s linear infinite;*/
            /*-webkit-animation: spread 2s linear infinite;*/
            /*-moz-animation: spread 2s linear infinite;*/
            /*-o-animation: spread 2s linear infinite;*/
        }
    </style>



</head>
<body>
<div></div>

</body>
</html>